Siemens SIMATIC S7-1500 System Manual page 264

Glossary
Row
All the modules attached to a mounting rail.
Runtime error
Error that occurs during execution of the user program in the automation system (thus not in
the process).
SELV
S afety E xtra Low V oltage = Safety extra-low voltage
Slave station
A slave may only exchange data with a master after being requested to by the master.
SNMP
SNMP (Simple Network Management Protocol) is the standardized protocol for performing
diagnostics on and assigning parameters to the Ethernet network infrastructure.
In the office setting and in automation engineering, devices from a wide range of vendors on
the Ethernet support SNMP.
SNMP-based applications can be operated on the same network in parallel to applications
with PROFINET.
The scope of supported functions varies depending on the device type. For example a switch
has more functions than a CP 1616.
Switch
PROFIBUS is a linear network. The communication nodes are linked by means of a passive
cable - the bus.
By contrast, Industrial Ethernet consists of point-to-point connections: each communication
node is interconnected directly with precisely one other communication node.
If a communication node is linked to several communication nodes, this communication node
is connected to the port of an active network component - the switch. Additional
communication nodes (including switches) can now be connected to the other ports of the
switch. The connection between a communication node and the switch remains a point-to-
point connection.
A switch thus has the task of regenerating and distributing received signals. The switch
"learns" the Ethernet address(es) of a connected PROFINET device or additional switches
and only forwards those signals that are intended for the connected PROFINET device or
switch.
A switch has a specific number of connections (ports). You connect at most one PROFINET
device or additional switch to each port.
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Automation system
System Manual, 09/2016, A5E03461182-AD